Quick Answer:
If an earthy or soil-like smell appears right after a water pressure change, it usually comes from organic buildup or sediment disturbed inside pipes, fixtures, or a water heater. Start by noting when the odor appears, run and isolate fixtures to find the source, and flush affected lines. If it persists or affects drinking water, get the water tested or call a plumber.
Why This Happens
Water systems collect organic material, biofilm, and fine sediment over time. Sudden pressure changes — from municipal main work, pump cycling, or a closed valve being opened — can create turbulence that dislodges that buildup. The freed material may release an earthy or musty odor as it flows through faucets or sits in traps and heaters. Localized smells often point to a single fixture or appliance; broad smells suggest a supply or distribution issue.
For smells that feel similar but appear in other situations you may find helpful information in Musty smell in tap water.
Step-by-Step What to Do
1. Log odor timing after pressure events
- Keep a simple note of when the pressure change happened and when the odor was noticed. Record which faucets were used, whether it was hot or cold water, and how long the smell lasted.
- This timeline helps you correlate the odor with municipal work, pump cycles, or specific fixtures.
2. Identify whether it’s local or whole-house
- Check multiple faucets (kitchen, bathroom, outdoor spigot) and both hot and cold. If only one fixture smells, the problem is local to that fixture or its trap.
- If many taps smell, suspect the main supply, water heater, or a well system.
3. Flush affected lines
- Run the cold water full force for several minutes at the affected tap(s) to clear dislodged material. Then run hot water to clear the heater and lines.
- If the odor follows the hot water only, flush the water heater according to the manufacturer’s basic guidance (drain a small amount to remove sediment), or have a pro do it.
4. Clean fixtures and traps
- Remove and clean aerators, faucet screens, and showerheads. Debris can collect there and emit odor when disturbed.
- Check P-traps and sink drains for organic buildup; cleaning them can remove odor sources. If you aren’t comfortable, ask a plumber.
5. Check recent work or supply changes
- Ask neighbors or your water utility if they had flushing or repairs recently. Pressure spikes from that work are a common cause.
- If you have a well, check the pressure tank and pump cycling; frequent cycling can stir up sediment.
6. Test the water if it’s persistent or worrying
- If the smell continues after flushing and cleaning, collect samples for a lab test or contact your water utility for guidance. Testing will rule out contamination and identify specific causes.
7. Track and repeat
- Continue logging odor occurrences after any new pressure event. This record helps a plumber or utility identify patterns and causes.
- If a bathroom sink is the recurring source, focus inspections there; you may find guidance under Moldy smell from bathroom sink.
What Not to Do
- Do not ignore pressure-related odor changes. Small problems can indicate larger supply or contamination issues.
- Do not assume boiling will fix every smell — boiling may not remove organic compounds that cause odors.
- Do not mix household chemicals in drains to “fix” odors. That can create dangerous fumes or reactions.
When to Call a Professional
- Call a plumber if the smell persists after flushing and cleaning, or if it’s limited to one fixture you can’t clear.
- Contact your water utility if multiple homes are affected or if the timing matches municipal work.
- If you suspect contamination of drinking water, arrange professional testing and remediation promptly.
Safety Notes
- Do not taste water to check for contamination. If water smells off, avoid drinking it until tested or confirmed safe.
- When cleaning traps or fixtures, wear gloves and ventilate the area. Dispose of waste water safely.
- If you use any disinfectant, follow product labels and avoid mixing chemicals.
Common Homeowner Questions
- Is it safe to drink water that smells earthy after a pressure change? Short answer: Avoid drinking until you’ve flushed lines and, if the smell persists, had the water tested.
- Can pressure changes release mold or bacteria from pipes? Short answer: Yes — pressure shifts can dislodge biofilm and organic buildup that produce moldy or earthy odors.
- Will boiling remove the earthy smell? Short answer: Boiling may not remove the compounds causing the smell; testing and addressing the source is better.
For more related articles, see the Musty, Earthy, or Moldy Water Smell hub.